1. Field of the Invention
The invention relates to a method and system for identifying the size of an optical disc, more particularly to a method and system for identifying the size of an optical disc within a relatively short period of time.
2. Description of the Related Art
Optical discs are currently available in standard sizes of eight-centimeter diameter and twelve-centimeter diameter. Motor control in a disc drive depends on the size of the optical disc. It is therefore necessary to identify the size of the optical disc prior to a read or write operation of the disc drive.
A conventional method for identifying the size of the optical disc includes moving an optical pickup head to a test position that is between eight and twelve centimeters from an initial position, and processing light detected by the optical pickup head. This method however requires a stepper motor for controlling the movement of the optical pickup head, and additional circuitries, thereby resulting in higher production costs.
In U.S. Pat. No. 5,644,561, there is disclosed another conventional method for identifying the size of the optical disc. The proposed method includes measuring the time necessary for the optical disc to reach a predetermined angular velocity or measuring the angular velocity of the optical disc after a predetermined time period. The measured time or angular velocity is then compared with a predetermined reference value to determine the size of the optical disc. Although the method proposed therein has its own merits, some waiting time is required for the optical disc to reach the predetermined angular velocity or before measuring of the angular velocity of the optical disc can be performed.